1. Field of the Invention
This invention relates generally to the field of heaters adapted for placement under a water bed mattress, more particularly to a flexible laminated heating pad having an associated temperature control unit.
2. Description of the Prior Art
Waterbed heaters typically consist of solid resistance wires or etched aluminum resistance elements which have been embedded or imprinted in a flat flexible mylar mat and sealed in a protective PVC sheath. Generally, the resistance elements are laid out in a serpentine pattern through the mat.
Numerous difficulties have been experienced with the aforementioned conventional heaters. First and foremost of the difficulties is that the heaters consume a tremendous amount of energy, since they have to heat anywhere from about 50 gallons of water for a child-sized waterbed to over 350 gallons of water for a king size bed. The high watt density of the heaters not only results in high costs to the waterbed owner, but also tends to accelerate waterbed mattress aging and can lead to electrical malfunctions. In addition, the heat distribution in conventional heaters tends to be uneven, causing "hot spots" in certain parts of the waterbed, while other parts are insufficiently heated. This may result in still more power consumption, since the waterbed user may be inclined to turn up the thermostat in order to heat up the cool parts of the mattress, even though the overall average temperature of the mattress might be satisfactory. Another problem of the prior art heaters is that because they have separate cables running from the mattress and heat sensor to the thermostat and the power supply they tend to be awkward and unwieldy. The cables cause lumps underneath the waterbed mattress, tend to tangle with one another, and make the pads more difficult to roll up for storage and transport. Thus, a need exists in the art for a new improved waterbed heater which heats the water in the waterbed mattress more efficiently and at the same time is less cumbersome and unwieldy than the prior art heaters.